用于直线感应加速器光源焦斑测量的双锥厚针孔结构设计

研究设计双锥厚针孔结构体,利用小孔成像测量高能强流直线感应加速器光源的焦斑。建立数值计算模型,根据实际光源特性和实验布局条件,模拟光子穿过厚针孔结构的辐射成像过程,分析光源尺寸、分布和偏轴等对焦斑测量的影响。理论计算结果显示对光源物面的空间分辨率可达5 lp/mm。     

直线感应加速器

本文描述了直线感应加速器（ＬＩＡ）的原理,组成和特点;综述了国内外的研究动态;概略介绍了ＣＡＥＰ流体物理研究所（ＩＦＰ）研制的１０ＭｅＶＬＩＡ．ＬＩＡ的技术特点和主要参数:可产生强脉冲Ｘ射线;打靶束流２．１ｋＡ,焦斑约４．５ｍｍ、距靶１ｍ处射线照射量约为２．３×１０￣（－２）ｃ／ｋｇ;该机前段（３．３ＭｅＶ）可与整机脱开、平移后与摇摆器（ｗｉｇｇｌｅｒ）对接,用于自由电子激光研究．对１０ＭｅＶＬＩＡ的关键技术研究和新的研究计划也作了描述． The basic principle,construction and characteristics of the LIA, together witha summary of the recent developments and achivements in the scientific field both at homeand abroad are presented in this paper.A10MeV LIA has been developed at IFP, CAEP forflash X-ray radiography application.A 2.4kA,70ns electron beam can be transportedthrough the accelerator, while 2.1kA is focused onto the target (Ta) With about 4mm spotto produce intensive pulsed X-ray.The dosage is 3×10￣(-2)C/kg at 1 meter from...     

直线感应加速器束包络数值计算模型

给出的直线感应加速器束输运的计算模型,能够计算束流从注入器经加速器直到最后聚焦的束包络.利用该编码可以方便地研究各种磁场位形及隙压参数对束流输运的影响.作为算例,给出了束流为3kA在长达40余米直线感应加速器的多种磁场位形下的束包络.     

直线感应加速器输运过程模拟

对直线感应加速器中电子束的输运过程进行数值模拟研究,采用了时域有限差分与粒子模拟相结合的方法。在对直线感应加速器建模的过程中,成功地使用了非均匀网格模型,实现了对加速腔精细结构的建模。并在加速间隙处加入了加速场。通过3个步骤实现了直线感应加速器加速腔中聚束磁场的模拟,最后将聚束场与加速段结合起来模拟电子束的输运过程,并对结果加以分析,验证了方法的正确性。     

12MeV直线感应电子加速器

 12MeV直线感应电子加速器(LIA)是经12MeV LIA能量升级和系统改进而来,该机通过在10MeV　LIA加速末端续接四个加速组元并调整脉冲功率系统, 将输出的电子束的能量升级至12MeV；同时,重新设计的输运磁场分布及聚焦系统更趋于合理,使经10MeV　LIA升级和改进后的12MeV　LIA，打靶电子束能量达到12MeV,束流约2.6kA，脉冲半高宽约89ns，焦斑约4 mm。     

12MeV直线感应电子加速器

12MeV直线感应电子加速器(LIA)是经12MeV LIA能量升级和系统改进而来,该机通过在10MeV　LIA加速末端续接四个加速组元并调整脉冲功率系统, 将输出的电子束的能量升级至12MeV;同时,重新设计的输运磁场分布及聚焦系统更趋于合理,使经10MeV　LIA升级和改进后的12MeV　LIA,打靶电子束能量达到12MeV,束流约2.6kA,脉冲半高宽约89ns,焦斑约4 mm。     

直线感应加速器输运过程模拟

对直线感应加速器中电子束的输运过程进行数值模拟研究,采用了时域有限差分与粒子模拟相结合的方法。在对直线感应加速器建模的过程中,成功地使用了非均匀网格模型,实现了对加速腔精细结构的建模。并在加速间隙处加入了加速场。通过3个步骤实现了直线感应加速器加速腔中聚束磁场的模拟,最后将聚束场与加速段结合起来模拟电子束的输运过程,并对结果加以分析,验证了方法的正确性。     

直线感应加速器模拟软件多功能发射模块开发

在模拟直线感应加速器电子束输运过程中,为了正确设置注入器电子束参数,以注发射模型为基础,研发了可设置发射度、能散和电子束倾斜的多功能发射模型。理论研究了发射度、能散以及电子束倾斜角度,并将这些理论实现到发射模块上。建模对多功能发射模块进行测试,比较设定的电子束参数与模拟测定的电子束参数。通过比较,观测到设定电子束参数与模拟测定值一致,验证了多功能模块开发的正确性。     

直线感应加速器束心偏移轨迹的计算

给出了直线感应加速器在磁体失准情况下电子束质心运动轨迹的计算机模型.利用坐标变换求磁体失准后的三维磁场分布,并采用束包络方程和束心偏移方程耦合求解的方法计算束心的运动轨迹.磁体失准度与束流质心偏移的定量关系的计算研究对磁体安装定位及校正线圈使用是有意义的.     

Influence of the energy and velocity spread in the electron beam on the starting conditions and efficiency of a gyrotron

We study theoretically the influence of the spread of initial energies and velocities in the electron beam on the starting conditions and efficiency of a gyrotron. We compare various analytical and numerical models and the results of experimental studies of gyrotrons in which the interaction takes place at the first and second harmonics of the cyclotron frequency. The aftercavity interaction of the electron beam with the high-frequency field in the output waveguide transition is taken into account. The influence of the energy spread on the recuperation efficiency is estimated. Permissible spreads of the initial energies and electron velocities are determined. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 2, pp. 121–133, February 2006.     

Observation of the anomalous increase of the longitudinal energy spread in a space-charge-dominated electron beam

We report a new experimental study of the growth of longitudinal energy spread in a space-charge-dominated electron beam, with a beam energy of several keV and beam current of approximately 100 mA. At relatively low beam densities, we measure growing energy spreads with distance along the transport channel, which are in remarkably good agreement with the theory of energy relaxation via Coulomb collisions. At higher beam densities, however, anomalous energy spreads exceeding the predictions of the relaxation theory are observed, which, we believe, could be caused by collective longitudinal-transverse instabilities observed in computer simulation studies. The onset of these instabilities occurs after several plasma periods according to calculations.     

A permanent magnet electron beam spread system used for a low energy electron irradiation accelerator

The development of irradiation processing industry brings about various types of irradiation objects and expands the irradiation requirements for better uniformity and larger areas. This paper proposes an innovative design of a permanent magnet electron beam spread system. By clarifying its operation principles, the author verifies the feasibility of its application in irradiation accelerators for industrial use with the examples of its application in electron accelerators with energy ranging from 300 keV to 1 MeV. Based on the finite element analyses of electromagnetic fields and the charged particle dynamics, the author also conducts a simulation of electron dynamics in magnetic field on a computer. The results indicate that compared with the traditional electron beam scanning system, this system boosts the advantages of a larger spread area, non-power supply, simple structure and low cost, etc., which means it is not only suitable for the irradiation of objects with the shape of tubes, strips and panels, but can also achieve a desirable irradiation performance on irregular constructed objects of large size.     

高能电子辐照对束测量系统的影响

在直线感应加速器束参数测量系统实验的基础上,给出了束参数测量系统的实验布局和特点,分析高能电子辐照对直线感应加速器中测量系统电子器件介电性能的影响和变化规律;进一步探讨电子器件介电性能受高能电子辐照后的抑制措施。针对电磁空间干扰情况,主要通过采用光纤传输控制信号的措施,能很好地传输窄脉冲,信号延时抖动小,达到了高速信号的可靠传输要求,利用紧凑嵌入式方法,提高了抗电磁干扰的能力,这样可以更好保护束参数测量电子器件。     

高能电子辐照对束测量系统的影响

在直线感应加速器束参数测量系统实验的基础上,给出了束参数测量系统的实验布局和特点,分析高能电子辐照对直线感应加速器中测量系统电子器件介电性能的影响和变化规律;进一步探讨电子器件介电性能受高能电子辐照后的抑制措施。针对电磁空间干扰情况,主要通过采用光纤传输控制信号的措施,能很好地传输窄脉冲,信号延时抖动小,达到了高速信号的可靠传输要求,利用紧凑嵌入式方法,提高了抗电磁干扰的能力,这样可以更好保护束参数测量电子器件。     

Fabrication and analysis of buried iron silicide microstructures using a focused low energy electron beam

We fabricated iron and iron silicide microstructures on an Si(1 0 0) clean surface via electron beam induced process of Fe(CO)₅ multilayer and subsequent annealing. The fabricated microstructures were in situ analyzed by Auger electron spectroscopy (AES) and scanning electron microscopy (SEM). We successfully analyzed the coverage and chemical states of the artificial deposited iron structure area-selectively by AES. The artificial iron structure was fabricated after heating to above 350 K to desorb residual Fe(CO)₅ species. The artificial structure was observed even after 1190 K annealing by SEM, but AES measurements showed it to be covered by Si atoms. We concluded that the buried iron silicide microstructure was formed by the present process.     

On the stability of a focused azimuthally homogeneous electron beam

The self-consistent field method is used to study the stability of an azimuthally homogeneous electron beam moving in a cylindrical resonator in a focusing magnetic field. Dispersion relations are derived and the harmonics of possible oscillations and the growth rates of resonance instabilities are determined.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 7, pp. 32–37, July, 1971.     

Determination of the profile of energy release from a high-power electron beam in an aerogel

Optical methods are used to investigate the dynamics of the interaction of a high-current electron beam with an aerogel (a highly porous transparent dielectric with a low density ρ=0.36 g/cm³). The measured profile of the glow of the aerogel and the pattern of its expansion are compared with the results of a numerical simulation. The influence of the space charge on the profile of the energy absorption from the high-current relativistic electron beam is discussed. Zh. Tekh. Fiz. 67, 26–32 (November 1997)     

Generating a uniform transverse distributed electron beam along a beam line

It has been reported that transverse distribution shaping can help to further enhance the energy extraction efficiency in a terawatt, tapered X-ray free-electron laser. Thus, methods of creating and keeping an almost uniform transverse distributed(UTD) beam within undulators are required. This study shows that a UTD electron beam can be generated within evenly distributed drift sections where undulators can be placed, by means of octupoles and particular optics. A specific design is presented, and numerical simulations are performed to verify the proposed method.     

强流短脉冲电子束束剖面测量技术

束流剖面信息的获得对于加速器的研究有着重要的意义。对强流短脉冲电子加速器束剖面测量技术作了评述。目前,发展时间分辨的快响应的光学测量技术及实时在线测量为主要发展趋势。